import java.util.LinkedList;
import java.util.Queue;

/**
 * Created with Intellij IDEA
 * Description
 * User:ASUS
 * Date:2024-09-11
 * Time:19:43
 */
public class MyStack {
    public Queue<Integer> qu1;
    public Queue<Integer> qu2;
    public MyStack(){
        qu1=new LinkedList<>();
        qu2=new LinkedList<>();
    }
    public void push(int x){
        if(!qu1.isEmpty()){
            qu1.offer(x);
        }else if(!qu2.isEmpty()){
            qu2.offer(x);
        }else{
            qu1.offer(x);
        }
    }
    public int pop(){
        if(empty()){
            return -1;
        }
        if(!qu1.isEmpty()){
            int size=qu1.size();
            for(int i=0;i<size-1;i++){
                qu2.offer(qu1.poll());
            }
            return qu1.poll();
        }else {
            int size=qu2.size();
            int val=0;
            for(int i=0;i<size-1;i++){
                qu1.offer(qu2.poll());
            }
            return qu2.poll();
        }
    }
    public int top(){
        if(empty()){
            return -1;
        }
        if(!qu1.isEmpty()){
            int size=qu1.size();
            int val=0;
            for(int i=0;i<size;i++){
                val=qu1.poll();
                qu2.offer(val);
            }
            return val;
        }else {
            int size=qu2.size();
            int val=0;
            for(int i=0;i<size;i++){
                val=qu2.poll();
                qu1.offer(val);
            }
            return val;
        }
    }
    public boolean empty(){
        return qu1.isEmpty()&&qu2.isEmpty();
    }
}
